Ultrasound biomicroscopic study of ciliary body thickness in eyes with narrow angles

To determine the ciliary body thickness and other biometric findings in eyes with narrow angles.

Eighteen otherwise normal eyes with narrow angles in 18 Japanese patients and 18 normal control eyes with open angles in 18 age-matched and sex-matched Japanese patients were studied. A-scan ultrasonography was performed to measure anterior chamber depth, lens thickness, axial length, and relative lens position. Ultrasound biomicroscopy was also performed to obtain measurements of the anterior ocular structures, including anterior chamber depth and ciliary body thickness at sites 1 mm and 2 mm posterior to the scleral spur (positions 1 and 2, respectively).

Compared with normal control eyes, the narrow-angle eyes showed a shallower anterior chamber (narrow angle, 1.87 +/- 0.27 mm; control, 2.69 +/- 0.26 mm; P <.0001), a thicker lens (4.97 +/- 0.49 mm, 4.26 +/- 0.53 mm; P <.0001), a more anteriorly located lens (2. 21 +/- 0.13, 2.35 +/- 0.14; P <.0001), a shorter axial length (22.70 +/- 0.97 mm, 23.41 +/- 0.86 mm; P =.012), and a thinner ciliary body (position 1: 454 +/- 107 microm, 602 +/- 86 microm; P <.0001; position 2: 203 +/- 50 microm, 321 +/- 68 microm; P <.0001). Lens thickness was significantly correlated with ciliary body thickness at positions 1 (R(2) = 0.34; P =.0001) and 2 (R(2) = 0.43; P <.0001). Anterior chamber depth was significantly correlated with ciliary body thickness at positions 1 (R(2) = 0.48; P <.0001) and 2 (R(2) = 0.56; P <.0001).

Thinning of the ciliary body may be one of the important factors associated with the anterior location of the lens, the increased lens thickness, and the decreased anterior chamber depth in eyes with a narrow angle.